Physicochemical Assessment, Pyrolysis and Thermal Characterization of Albizia Zygia Tree Sawdust

Abstract

Standard methods were used to obtain proximate and ultimate parameters of Albizia zygia tree sawdust. The HHV of 16.01 MJ/ Kg, H/C of 0.127, O/C of 0.96, high volatile matter of 87.85 wt.% and low ash content of 1.55 wt.% Albizia zygia sawdust makes it a good biofuel. Its empirical formula from elemental ratios combination is CH0.127 O0.96 N0.057 . There were insignificant volumes of oxides of nitrogen and sulphur produced during its pyrolysis since %N & %S are relatively low (2.63 & 0) wt.% respectively. Its TG/DTG profile showed devolatilization of sawdust began at 230 o C and the pyrolysis temperature was in the range of 420- 600 o C. Its fixed bed pyrolysis recorded maximum value of bio-oil at 450 o C. FTIR analysis confirmed the presence of oxygenated compounds in the sawdust and its crude bio-oil. The analysis of the obtained bio-oil using GC-FID showed that significant quantity of -OH compounds were produced from the sawdust through pyrolysis though the obtained quantity is not economical. Sintering and slagging-fouling indicators such as; [Na2 O + K2 O] / [SiO2 ]= 0.0695 showed (unlikely sintering inclination); Base/Acid=0.438 (low ash deposition tendency); [SiO2 ]/([Al2 O3 ]=5.44 & [Fe2 O3 ] / [CaO]=0.28 (low ash deposition tendencies respectively); slagging viscosity index= 68.58 (low slagging tendency); %(SiO2 )=55.18 (high); Babcock (Rs)= 4.38x 10-5 & Fouling indices (Fu)= 1.68x10-2 (low deposition tendencies); Total alkalis (TA) =0.0097 ( Low fouling tendency). It can be projected that improvement on pyrolysis process parameters and pre-treatment of sawdust can be used to achieve higher yield of bio-oil then consequently leading to higher quantity of alcohol compounds.